1. Field of the Invention
The present invention relates to a variable density fluid, and more specifically, relates to such a fluid comprising a multiplicity of polymer micro-particles suspended in a fluid. The invention further relates to a variable viscosity fluid, and more specifically relates to such a fluid comprising a multiplicity of polymer microfilaments suspended in a fluid. The present invention further relates to a variable compressibility fluid.
The present invention also relates to an inexpensive, non-toxic fluid which can be pumped and valved similarly to water but having a much lower bulk density. Such a low density fluid reduces the pressure and weight requirements of containing vessels, conduits and pumps.
In one embodiment of the present invention, the microparticles are modified to remove liquid hydrocarbon contaminants from another liquid, such as water. This embodiment is particularly useful in the clean-up of oil spills on ocean water.
2. Description of the Prior Art
Polymer micro-particles have found wide acceptance for many purposes, but in particular have been used in both the latex coating and oil spill clean-up fields. U.S. Pat. No. 3,755,238, granted to Wiita on Aug. 28, 1978, discloses a latex coating composition having dispersed therein finely divided polyolefin particles having a particle size from 8 to 30 microns. Wiita discloses that the addition of polyolefin particles substantially reduces blocking while maintaining good gloss characteristics in the vinyl resin latex coatings. Similarly, U.S. Pat. No. 3,941,736, granted to Aldrich on Mar. 2, 1976, discloses an aqueous dispersion of hydrocarbon resin in finely divided form to be used in applications such as sizing paper.
In the hydrocarbon contaminant removal field, U.S. Pat. No. 4,230,566, granted to Faudree on Oct. 28, 1980, discloses a method of producing a granular polyurethane cellular foam for absorbing water-borne, water insoluble hydrocarbons. Faudree teaches the production of a low density cellular polymer through the steps of pre-heating a polyisocyanate with a linear monohydric alcohol to form a prepolymer having a greater surface affinity for oils or similar contaminant hydrocarbons; combining the prepolymer with a polyol in the presence of a blowing agent and reacting said mixture in a mold to effect exothermic cellular polymeric formation; and grinding the cellular polymeric formation to a granular size. Faudree further teaches that the grinding step causes the cells in the closed cell foam to rupture. These ruptured cells tend to hold the oil within their open cavities and thus promote their own buoyancy. The pre-reaction of the organic polyisocyanate linear monohydric alcohol creates a prepolymer whose outer surface has a high affinity for oils and is thus hydrophobic.
U.S. Pat. No. 3,657,125, granted to Strickman on Apr. 18, 1972, discloses a method of removing oil from a mixture of oil and water comprising contacting the oil with polyurethane collector granules having jagged, spiney, cragged forms devoid of cellular structure and having a particle size between 50 and 750 microns.
Thus, there has been a need in the liquid hydrocarbon contamination removal art for an effective and easily manufactured means for selectively removing liquid hydrocarbon contaminants from other liquids, such as oil slicks from ocean water for example.
Furthermore, there has been a need in the fluid arts for a fluid whose density may be varied as desired. More specifically, there has been a need in the art for an inexpensive, non-toxic fluid having properties similar to water but having a much lower bulk density.
There has been a further need for a low density fluid having a specific heat and thermal conductivity similar to that of the suspending fluid, such as water for example.
There has been a still further need in the fluid arts for a fluid having a controllable compressibility.
There has been a still further need in the fluid arts for a fluid whose viscosity may be controlled and varied as desired.